Butadiene is one of the three important olefins produced in petrochemical process, and has a wide range of application perspective. At present, butadiene is primarily used as the raw material for producing high molecular synthetic material such as polybutadiene rubber, styrene butadiene rubber (SBR) and so on in bulk. But with the development of science and technology, butadiene oligomer products production technology becomes more mature, its application becomes more extensive, and the researchers become more interested in studying oligomerization technology. Among them, an attracting one is the trimerization of butadiene to 1,5,9-cyclododecatriene (CDT). CDT is an important fine chemical intermediate, and its very important uses are the production of engineering plastics nylon 12, polyamide, flame retardant, and certain macrocyclic musks. In order to obtain nylon 12, CDT is firstly converted to polyol, and then formed into nylon 12. Polyamides (PA) obtained by polycondesation of diamines and diacids or by polymerization of lactams are the most popular and commonly used polymers. Among the polyamides, only poly-ε-caprolactam (PA6), poly-ω-undecalactam (PA11) and poly-ω-dodecalactam (PA12) can be available for industrial use. PA12 contains less residual monomers in the molecule, has a low atmospheric moisture absorption capacity, and can maintain good toughness at very low temperatures (−70° C.). Thus, PA12 is often used to manufacture high quality plastic articles, particularly those intended to use in the environment varied frequently in humidity or those required to have good mechanical properties, heat insulation and electrical insulation properties. In addition, it can be used in the protective sheath of cables, ducts and pipes, pneumatic brake pipes and pipelines of the fuel system for automobiles. Most of the known methods for producing PA12 use cyclododecatriene prepared by trimerization of butadiene as the raw material.
Since Wilke separated a metal nickel coordination complex from butadiene oligomers, the cyclooligomerization process of butadiene has been set forth. And the theory of the butadiene cyclooligomerization and the production technology have gradually come to maturity. CDT was used as the dodecalactam raw materials of nylon 12 from 1970s in the former West Germany etc., and therefore there have been cases of the development of industrial scale production. A bromination reaction product of CDT, i.e., hexabromocyclododecane (HBCD), has been used as the flame retardant of engineering plastics which will be one of the needs for CDT in future. In China, the use of HBCD as the flame retardant for textile was studied in lab, but was not practiced in the industrial application. The macrocyclic muscone (TM-II) products with natural perfumes from animal have been prepared by Japan Toray Industries, Inc. using CDT as the raw material and sold in the market. With the enlarged application of the CDT products, there is an increasing demand for CDT in the market.
Homogeneous titanium-based Ziegler-Natta catalysts have been applied for the industrial trimerization of butadiene since 1956, and still have the disadvantages of low selectivity, poor activity, etc. These catalyst systems have been studied in Dalian Institute of Chemical Physics, Chinese Academy of Sciences and the Research Institue of Rubber Factory of SINOPEC BEIJING YANSHAN COMPANY at the lab- and pilot-scale in 1990s, but the industrial application is not reported.
U.S. Pat. No. 3,634,528 disclosed the trimerization of butadiene using organotitanium/hydrocarbyl aluminium chloride as the catalyst and benzene as the solvent, having the conversion of butadiene of at most 95.6%, but there is no data about the catalyst activity and CDT selectivity of the reaction products. U.S. Pat. No. 3,523,980 disclosed the trimerization of butadiene using sesquiethyl aluminum chloride/oxygen/titanium (IV) compound as the catalyst system. The disclosure discussed the influences of the molar ratio of sesquiethyl aluminum chloride/titanium (IV) compound to oxygen on the reactivity, but the selectivity was not described. U.S. Pat. No. 3,658,926 disclosed the trimerization of butadiene using tetrabutyl titanium/triphenyl phosphine/triethyl aluminium as the catalyst system, but the activity and selectivity were not described. U.S. Pat. No. 3,655,795 disclosed the trimerization of butadiene using a titanium compound/an organoaluminium compound/a promoter as the catalyst, and mainly discussed the influences of different promoters, such as water, oxgenated compounds, oxygen or oxygen containing gases or liquids on the catalytic properties. U.S. Pat. No. 3,636,174 also disclosed a similar catalyst, which was different from that of U.S. Pat. No. 3,655,795 only in the promoter. Using the sulfoxide as the promoter, its catalytic activity may be up to 11238.8 g CDT/g Ti/h, but the CDT selectivity of the reaction products was not described. The Research Institue of Rubber Factory of SINOPEC BEIJING YANSHAN COMPANY also studied the catalyst system in 1990s, and found that the catalyst has the optimal catalytic activity of 18220 g CDT/g Ti/h, and CDT selectivity of the reaction products of 93.84% at high pressure. Its catalytic activity and CDT selectivity are still low.
Although the process for catalyzing the trimerization of butadiene to CDT using the titanium-based catalysts has been applied for the industrial production since 1956, it still has suffered the low catalyst activity, low selectivity etc.